Red-capped mangabeys (Cercocebus torquatus) adapt their interspecific gestural communication to the recipient\u2019s behaviour

Juliette Aychet,Philippe Bec,Pablo Pezzino,Arnaud Rossard,Catherine Blois-Heulin,Alban Lemasson

doi:10.1038/s41598-020-69847-6

Abstract

Sensitivity to recipient’s attention and responsiveness are critical markers of intentional communication. Although previous research showed that ape gestures can be intentional, few studies have yet addressed this question concerning monkeys. Here, we characterise the effect of a recipient’s presence, attentional state and responsiveness on the interspecific gestural communication of captive red-capped mangabeys (Cercocebus torquatus). Previous reports showed that they produced learnt begging gestures towards a human recipient preferentially when the latter was facing them. We used here a novel setup that allows subjects to move around an experimenter and to use different modalities (visual and acoustic) to communicate. We found that when the recipient was not facing them, mangabeys moved to a position in the visual field of their recipient rather than using attention-getters. Interestingly, unlike apes, they did not elaborate their communication visually or acoustically when the experimenter did not respond favourably to their begging. However, our results may suggest that begging gestures were goal-directed, since mangabeys inhibited them when the experimenter was not available to answer immediately (i.e. give a reward). Overall, red-capped mangabeys’ interspecific visual communication presented intentionality features, but their use of begging gestures was less flexible than that of great apes in similar situations.

Highlights

Intentionality of non-human primate communication is a key feature for the study of language o rigins[1,2]
Reports showed that chimpanzees moved so that they could stay in front of their human recipient before gesturing[23], and a recent study demonstrated this ability in wild bonnet macaques[33]
In an intentional communication event, a signaller can be expected to act strategically in order to reach its goal, and so to persist or to elaborate its communication when the recipient does not give a satisfying answer[9,10]. Both persistence and elaboration were brought to light in great a pes[12,13,59,60], notably using experimental paradigms of interspecific communication where a human either does not give a response or gives a partial response to an ape’s begging gestures[8,25]. We addressed all these aspects of intentionality on the gestural communication of a still poorly studied species of catarrhine monkeys, the red-capped mangabey (Cercocebus torquatus), via an experimental approach in captivity

Summary

Introduction

Intentionality of non-human primate communication is a key feature for the study of language o rigins[1,2]. Reports showed that chimpanzees moved so that they could stay in front of their human recipient before gesturing[23], and a recent study demonstrated this ability in wild bonnet macaques[33] To our knowledge, this has not yet been investigated in other catarrhine or platyrrhine monkeys, several species are known to be sensitive to a recipient’s attentional state for displaying begging gestures, based on the human’s head or body posture (olive b aboons[28]; red-capped mangabeys[27]; Tonkean and rhesus macaques[31,38]; capuchin m onkeys[39,40]). We tested the effect of different recipient’s response on the gestural communication of mangabeys, hypothesising that (vi) they would persist in gesturing if the recipient did not respond favourably to their begging, or (vii) would elaborate their communication visually (by changing their gesture amplitude, or producing other visual signals) or acoustically (by producing audible gestures or vocalisations)

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Discussion

Conclusion